national accelerator – Polkinghorne http://polkinghorne.org/ Thu, 17 Mar 2022 18:30:28 +0000 en-US hourly 1 https://wordpress.org/?v=5.9.3 https://polkinghorne.org/wp-content/uploads/2022/01/icon-2022-01-25T202759.511-150x150.png national accelerator – Polkinghorne http://polkinghorne.org/ 32 32 New results from MicroBooNE provide clues to the mystery of particle physics https://polkinghorne.org/new-results-from-microboone-provide-clues-to-the-mystery-of-particle-physics/ Thu, 28 Oct 2021 07:00:00 +0000 https://polkinghorne.org/new-results-from-microboone-provide-clues-to-the-mystery-of-particle-physics/ MicroBooNE detector being lowered into the Fermilab experimental facility. Credit: Fermilab New results from a more than a decade-long physics experiment offer insight into unexplained electronic-like events discovered in previous experiments. The results of the MicroBooNE experiment, while not confirming the existence of a proposed new particle, the sterile neutrino, open the way to exploring […]]]>

MicroBooNE detector being lowered into the Fermilab experimental facility. Credit: Fermilab

New results from a more than a decade-long physics experiment offer insight into unexplained electronic-like events discovered in previous experiments. The results of the MicroBooNE experiment, while not confirming the existence of a proposed new particle, the sterile neutrino, open the way to exploring physics beyond the Standard Model, the fundamental force theory of nature and elementary particles.

“The results so far from MicroBooNE make the explanation for the electronic-like anomalous events of the MiniBooNE experiment more likely to be physics beyond the Standard Model,” said William Louis, a physicist at Los Alamos National Laboratory. and member of the MicroBooNE collaboration. “What exactly the new physics is remains to be seen.”

The MicroBooNE experiment at the US Department of Energy’s Fermi National Accelerator Laboratory explores a striking anomaly in particle beam experimentation first discovered by researchers at Los Alamos National Laboratory. In the 1990s, the liquid scintillator neutrino detector experiment at the Laboratory saw more electron-like events than expected, compared to calculations based on the Standard Model.

In 2002, the MiniBooNE follow-up experiment at Fermilab began collecting data to further investigate the LSND outcome. MiniBooNE scientists also saw more electronic-like events than calculations based on the Standard Model prediction. But the MiniBooNE detector had a particular limitation: it was unable to tell the difference between electrons and photons (particles of light) near where the neutrino was interacting.

The MicroBooNE experiment seeks to explore the source of the anomaly for additional events. The MicroBooNE detector is built on state-of-the-art techniques and technology, using special light sensors and over 8,000 painstakingly attached wires to capture particle trails. It is housed in a 40-foot-long cylindrical container filled with 170 tons of pure liquid argon. The neutrinos hit the dense, transparent liquid, releasing additional particles that the electronics can record. The resulting images show detailed particle trajectories and, importantly, distinguish electrons from photons.

“Liquid argon technology is relatively new in neutrino physics, and MicroBooNE has been a pioneer for this technology, demonstrating what amazing physics can be done with it,” said Sowjanya Gollapinni, laboratory physicist and co-lead of analysis. “We had to develop all the tools and techniques from scratch, including how to process the signal, how to reconstruct it, and how to do the calibration, among other things.”

MicroBooNE included a series of measurements: one measurement of photons and three measurements of electrons. In early October, the results of the photon measurement, which specifically looked for Delta radiative decay, provided the first direct evidence disfavoring an excess of neutrino interactions due to this abnormal single photon production as an explanation for the excess of MiniBooNE energy. Delta radiative decay was the only background that the MiniBooNE experiment could not directly constrain.

The three new electron analyzes address the question of whether the excess is due to the scattering of an electron neutrino off an argon nucleus, producing an outgoing electron. The new results disfavor this process as an explanation for excess MiniBooNE, leaving the question of what causes the MiniBooNE anomaly still unanswered.

“In my mind, the fact that neither photon nor electron production explains the excess makes understanding the MiniBooNE results more interesting and more likely to venture into some very interesting physics beyond the Standard Model. “, said Louis.

New results from MicroBooNE provide clues to the mystery of particle physics

Interior of the MicroBooNE Time Projection Chamber detector. Credit: Fermilab

With only half of the MicroBooNE data still evaluated, possible explanations yet to be considered (or tested in future experiments) include the possibility that as yet unproven sterile neutrinos could decay into gamma rays. The decay of the axion – the axion is another hypothetical elementary particle – into gamma or an electron-positron pair could also be responsible. Neutrinos and sterile axions could be linked to the dark sector, the hypothetical realm of yet unobserved different physics and particles.

“The possibilities are endless,” Gollapinni said, “and MicroBooNE will be on a mission to explore each one with the full data set. The results pave the way for further physics experiments, but a full understanding of the results will also depend on our colleagues in theoretical physics, who are very intrigued by these results.”

MicroBooNE is part of a suite of neutrino experiments looking for answers. The ICARUS detector starts collecting physical data and the Short Baseline Proximity Detector (SBND) will come online in 2023; both detectors use liquid argon technology. Together with MicroBooNE, the three experiments form Fermilab’s short-base neutrino program and will yield a wealth of neutrino data. For example, in one month, SBND will record more data than MicroBooNE collected in two years. Today’s results from MicroBooNE will help guide some of the research in the trio’s extensive portfolio.

Building further on MicroBooNE’s techniques and technology, liquid argon will also be used in the Deep Underground Neutrino Experiment (DUNE), a flagship international experiment hosted by Fermilab which already has more than 1,000 researchers from over 30 countries. DUNE will study the oscillations by sending neutrinos 1,300 km (800 miles) through the earth to detectors at the underground research center in Sanford, South Dakota. Combining short- and long-range neutrino experiments will give researchers insight into how these fundamental particles work.

At Fermilab or underground in South Dakota, Laboratory researchers bring the technology and analytical understanding to probe the mysteries of particle physics. What awaits us is unknown, but exciting.

“What we have found and continue to find with MicroBooNE will have important implications for future experiments,” Gollapinni said. “These results point us in a new direction and tell us to think outside the box. MicroBooNE’s journey to explore the exciting physics that awaits us has just begun, and there is much more that MicroBooNE will reveal in the years to come.”


Scientists find no trace of sterile neutrino


Provided by Los Alamos National Laboratory

Quote: New results from MicroBooNE provide clues to the mystery of particle physics (2021, October 28) retrieved February 15, 2022 from https://phys.org/news/2021-10-results-microboone-clues-particle -physics.html

This document is subject to copyright. Except for fair use for purposes of private study or research, no part may be reproduced without written permission. The content is provided for information only.

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New MicroBooNE Results Provide Clues to Particle Physics Mystery – Los Alamos Reporter https://polkinghorne.org/new-microboone-results-provide-clues-to-particle-physics-mystery-los-alamos-reporter/ Wed, 27 Oct 2021 07:00:00 +0000 https://polkinghorne.org/new-microboone-results-provide-clues-to-particle-physics-mystery-los-alamos-reporter/ MicroBooNE detector being lowered into the Fermilab experimental facility. Photo courtesy Fermilab LANL PRESS RELEASE New results from a more than a decade-long physics experiment offer insight into unexplained electronic-like events discovered in previous experiments. The results of the MicroBooNE experiment, while not confirming the existence of a proposed new particle, the sterile neutrino, open […]]]>

MicroBooNE detector being lowered into the Fermilab experimental facility. Photo courtesy Fermilab

LANL PRESS RELEASE

New results from a more than a decade-long physics experiment offer insight into unexplained electronic-like events discovered in previous experiments. The results of the MicroBooNE experiment, while not confirming the existence of a proposed new particle, the sterile neutrino, open the way to exploring physics beyond the Standard Model, the fundamental force theory of nature and elementary particles.

“The results so far from MicroBooNE make the explanation for the electronic-like anomalous events of the MiniBooNE experiment more likely to be physics beyond the Standard Model,” said William Louis, physicist at Los Alamos National Laboratory. and member of the MicroBooNE collaboration. “What exactly the new physics is – that remains to be seen.”

The MicroBooNE experiment at the US Department of Energy’s Fermi National Accelerator Laboratory explores a striking anomaly in particle beam experimentation first discovered by researchers at Los Alamos National Laboratory. In the 1990s, the liquid scintillator neutrino detector experiment at the Laboratory saw more electron-like events than expected, compared to calculations based on the Standard Model.

In 2002, the MiniBooNE follow-up experiment at Fermilab began collecting data to further investigate the LSND outcome. MiniBooNE scientists also saw more electronic-like events than calculations based on the Standard Model prediction. But the MiniBooNE detector had a particular limitation: it was unable to tell the difference between electrons and photons (particles of light) near where the neutrino was interacting.

The MicroBooNE experiment seeks to explore the source of the additional event anomaly. The MicroBooNE detector is built on state-of-the-art techniques and technology, using special light sensors and over 8,000 painstakingly attached wires to capture particle trails. It is housed in a 40-foot-long cylindrical container filled with 170 tons of pure liquid argon. The neutrinos hit the dense, transparent liquid, releasing additional particles that the electronics can record. The resulting images show detailed particle trajectories and, importantly, distinguish electrons from photons.

“Liquid argon technology is relatively new in neutrino physics, and MicroBooNE has been a pioneer for this technology, demonstrating what amazing physics can be done with it,” said Sowjanya Gollapinni, laboratory physicist and co-lead of analysis. “We had to develop all the tools and techniques from scratch, including how to process the signal, how to reconstruct it, and how to do the calibration, among other things.”

MicroBooNE included a series of measurements: one measurement of photons and three measurements of electrons. In early October, the results of the photon measurement, which specifically looked for Delta radiative decay, provided the first direct evidence disfavoring an excess of neutrino interactions due to this abnormal single photon production as an explanation for the excess of MiniBooNE energy. Delta radiative decay was the only background that the MiniBooNE experiment could not directly constrain.

The three new electron analyzes address the question of whether the excess is due to the scattering of an electron neutrino off an argon nucleus, producing an outgoing electron. The new results disfavor this process as an explanation for excess MiniBooNE, leaving the question of what causes the MiniBooNE anomaly still unanswered.

“In my mind, the fact that neither photon nor electron production explains the excess makes understanding the MiniBooNE results more interesting and more likely to venture into some very interesting physics beyond the Standard Model. “, said Louis.

With only half of the MicroBooNE data still evaluated, possible explanations yet to be considered (or tested in future experiments) include the possibility that as yet unproven sterile neutrinos could decay into gamma rays. The decay of the axion – the axion is another hypothetical elementary particle – into gamma or an electron-positron pair could also be responsible. Neutrinos and sterile axions could be linked to the dark sector, the hypothetical realm of yet unobserved different physics and particles.

“The possibilities are endless,” said Gollapinni, “and MicroBooNE will be on a mission to explore each one with the full data set. The results pave the way for further experiments in physics, but a full understanding of the results will also depend on our colleagues in theoretical physics, who are very intrigued by these results.

MicroBooNE is part of a suite of neutrino experiments looking for answers. The ICARUS detector starts collecting physical data and the Short Baseline Proximity Detector (SBND) will come online in 2023; both detectors use liquid argon technology. Together with MicroBooNE, the three experiments form Fermilab’s short-base neutrino program and will yield a wealth of neutrino data. For example, in one month, SBND will record more data than MicroBooNE collected in two years. Today’s results from MicroBooNE will help guide some of the research in the trio’s extensive portfolio.

Building further on MicroBooNE’s techniques and technology, liquid argon will also be used in the Deep Underground Neutrino Experiment (DUNE), a flagship international experiment hosted by Fermilab which already has more than 1,000 researchers from over 30 countries. DUNE will study the oscillations by sending neutrinos 1,300 km (800 miles) through the earth to detectors at the underground research center in Sanford, South Dakota. Combining short- and long-range neutrino experiments will give researchers insight into how these fundamental particles work.

At Fermilab or underground in South Dakota, Laboratory researchers bring the technology and analytical understanding to probe the mysteries of particle physics. What awaits us is unknown, but exciting.
“What we have found and continue to find with MicroBooNE will have important implications for future experiments,” Gollapinni said. “These results point us in a new direction and tell us to think outside the box. MicroBooNE’s journey to explore the exciting physics that awaits us has just begun, and there is much more that MicroBooNE will reveal in the years to come.

Inside the MicroBooNE Time Projection Chamber detector.pPhoto courtesy of Fermilab

MicroBooNE is supported by the US Department of Energy, US National Science Foundation, Swiss National Science Foundation, UK Science and Technology Facilities Council, UK Royal Society and European Union Horizon 2020.

On Los Alamos National Laboratory
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Triad, a public service-focused national security science organization equally owned by its three founding members. : the Battelle Memorial Institute (Battelle), the Texas A&M University System (TAMUS), and the University of California (UC) Regents for the Department of Energy’s National Nuclear Security Administration.

Los Alamos strengthens national security by ensuring the safety and reliability of America’s nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and addressing issues related to energy, environment, infrastructure, to global health and security issues.

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Muons don’t fit the standard model of particle physics https://polkinghorne.org/muons-dont-fit-the-standard-model-of-particle-physics/ Fri, 16 Apr 2021 07:00:00 +0000 https://polkinghorne.org/muons-dont-fit-the-standard-model-of-particle-physics/ Share this Item You are free to share this article under the Attribution 4.0 International License. Fundamental particles called muons behave in ways that scientists’ best theory to date, the Standard Model of particle physics, does not predict, the researchers report. The discovery comes from early results from the Muon g-2 experiment at the US […]]]>

Fundamental particles called muons behave in ways that scientists’ best theory to date, the Standard Model of particle physics, does not predict, the researchers report.

The discovery comes from early results from the Muon g-2 experiment at the US Department of Energy’s Fermi National Accelerator Laboratory.

“This experience is a bit like a detective novel.”

This historic result confirms a discrepancy that has plagued researchers for decades.

The strong evidence that muons deviate from the Standard Model calculation could hint at some exciting new physics. The muons in this experiment act as a window into the subatomic world and could interact with as yet unknown particles or forces.

“This experiment is a bit like a detective novel,” says team member David Hertzog, a University of Washington physics professor and founding spokesperson for the experiment. “We analyzed data from the inaugural Muon g-2 test at Fermilab and discovered that the Standard Model alone cannot explain what we found. Something else, perhaps beyond the standard model, may be required. »

A muon is about 200 times more massive than its cousin the electron. They occur naturally when cosmic rays hit the Earth’s atmosphere. Fermilab’s particle accelerators can produce large numbers of them. Like electrons, muons act as if they have a small internal magnet. In a strong magnetic field, the direction of the muon magnet precedes, or “wobbles,” much like the axis of a spinning top. The strength of the internal magnet determines the muon’s precession rate in an external magnetic field and is described by a number known as the g-factor. This number can be calculated with ultra-high precision.

As muons flow through the Muon g-2 magnet, they also interact with a “quantum foam” of subatomic particles that appear and disappear. Interactions with these short-lived particles affect the value of the g-factor, causing muon precession to accelerate or slightly slow down. The standard model predicts with great accuracy what the value of this “abnormal magnetic moment” should be. But if the quantum foam contains additional forces or particles not accounted for by the Standard Model, it would further alter the g-factor of the muon.

Hertzog, then at the University of Illinois, was a lead scientist in the previous experiment at Brookhaven National Laboratory. This attempt ended in 2001 and offered clues that the behavior of the muon did not conform to the Standard Model. The new measurement from the Muon g-2 experiment at Fermilab strongly agrees with the value found at Brookhaven and deviates from theory with the most accurate measurement to date.

The accepted theoretical values ​​for the muon are:

  • g-factor: 2.00233183620(86)
  • abnormal magnetic moment: 0.00116591810(43)

The new experimental global mean results announced today by the Muon g-2 collaboration are:

  • g-factor: 2.00233184122(82)
  • abnormal magnetic moment: 0.00116592061(41)

The combined results from Fermilab and Brookhaven show a difference with theoretical predictions at a significance of 4.2 sigma, a little short of the 5 sigma – or 5 standard deviations – that scientists prefer as a claim of discovery. But it’s still compelling evidence of new physics. The probability that the results are a statistical fluctuation is approximately 1 in 40,000.

“This result from the first run of the Fermilab Muon g-2 experiment is arguably the most anticipated result in particle physics in recent years,” says Martin Hoferichter, assistant professor at the University of Bern and member of the theoretical collaboration that predicts the value of the standard model. “After almost a decade, it’s great to see this massive effort finally come to fruition.”

The Fermilab experiment, which is underway, reuses the main component of the Brookhaven experiment, a superconducting magnetic storage ring 50 feet in diameter. In 2013, it was transported 3,200 miles by land and sea from Long Island to suburban Chicago, where scientists were able to take advantage of Fermilab’s particle accelerator and produce the states’ most intense muon beam. -United. Over the next four years, researchers mounted the experiment; tuned and calibrated an incredibly uniform magnetic field; developed new techniques, instruments and simulations; and thoroughly tested the entire system.

The Muon g-2 experiment sends a beam of muons into the storage ring, where they circulate thousands of times at near the speed of light. Detectors lining the ring allow scientists to determine how fast muons “wobble”.

Many Fermilab sensors and detectors have been built at the University of Washington, such as instruments to measure the muon beam as it enters the storage ring and to detect the telltale particles that appear when the muons decay . Dozens of scientists – including professors, postdoctoral researchers, technicians, graduate students and undergraduates – worked to assemble these sensitive instruments, then set them up and monitor them at Fermilab.

“The outlook for the new result has triggered a coordinated theoretical effort to provide our experimental colleagues with a robust and consensus prediction of the Standard Model,” says Hoferichter. “Future runs will motivate further refinements, to enable a conclusive statement whether physics beyond the Standard Model lurks in the muon’s anomalous magnetic moment.”

In its first year of operation, 2018, the Fermilab experiment collected more data than all previous muon g-factor experiments combined. The Muon g-2 collaboration has now completed the analysis of the movement of more than 8 billion muons from this first period.

Analysis of data from the second and third cycles of the experiment is in progress; the fourth is in progress and a fifth is planned. Combining the results from all five tests will give scientists an even more precise measurement of the muon’s ‘wobble’, revealing with greater certainty whether new physics is lurking in the quantum foam.

“So far, we’ve analyzed less than 6% of the data the experiment will eventually collect,” says Fermilab scientist Chris Polly, who is a co-spokesperson for the current experiment and was a graduate student. of the University of Illinois under Hertzog during the Brookhaven Experiment. “While these early results tell us there is an intriguing difference to the standard model, we will learn much more over the next two years.”

“With these exciting results, our team, especially our students, are excited to push hard on analyzing the remaining data and taking future data to achieve our ultimate goal of accuracy,” says Peter Kammel, research professor of physics at the University of Washington.

An article on the research appears in Physical examination letters. Hertzog will present the findings at a University of Washington Physics Department Symposium on April 12.

The Muon g-2 experiment is an international collaboration between Fermilab in Illinois and more than 200 scientists from 35 institutions in seven countries.

Source: University of Washington

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Brookhaven Lab Appoints New Director of Nuclear and Particle Physics Branch https://polkinghorne.org/brookhaven-lab-appoints-new-director-of-nuclear-and-particle-physics-branch/ Thu, 15 Apr 2021 07:00:00 +0000 https://polkinghorne.org/brookhaven-lab-appoints-new-director-of-nuclear-and-particle-physics-branch/ Haiyan Gao, nuclear physicist and professor, will join the lab as associate lab director for nuclear and particle physics UPTON, NY – Haiyan Gao, currently the Henry W. Newson Professor Emeritus of Physics at Duke University, will join the U.S. Department of Energy’s Brookhaven National Laboratory as Associate Laboratory Director (ALD) for Nuclear Physics and […]]]>

Haiyan Gao, nuclear physicist and professor, will join the lab as associate lab director for nuclear and particle physics

UPTON, NY – Haiyan Gao, currently the Henry W. Newson Professor Emeritus of Physics at Duke University, will join the U.S. Department of Energy’s Brookhaven National Laboratory as Associate Laboratory Director (ALD) for Nuclear Physics and particles (NPP) from or around June 1, 2021.

Gao, who has a long background in nuclear physics, will help develop Brookhaven’s collective long-term vision for the next 10 years. She will also work throughout the lab and beyond to develop her emerging expertise at the future Electron-Ion Collider (EIC), a one-of-a-kind nuclear physics research facility to be built at the lab over the next decade after Brookhaven’s flagship nuclear physics facility, the Relativistic Heavy Ion Collider, completes its research mission.

“The Nuclear and Particle Physics Branch is internationally well-known in the fields of accelerator science, high-energy physics and nuclear physics,” Gao said. “I am very excited about the opportunity and the impact that I will be able to have in collaboration with many people at the Lab.”

Gao will replace ALD Deputy for High Energy Physics Dmitri Denisov, who became interim NPP ALD after Berndt Mueller left office last year to return to teaching and research full-time at Duke.

“We are delighted to welcome Haiyan to Brookhaven at such an exciting time for nuclear and particle physics,” said Brookhaven Laboratory Director Doon Gibbs. “His perspective and experience will be instrumental in advancing science here in the lab and beyond.”

Gao joins Brookhaven Lab as he develops the EIC in collaboration with scientists at the DOE’s Thomas Jefferson National Accelerator Facility. The EIC will offer scientists a deeper look at the building blocks of visible matter and the most powerful force in nature.

“What’s important in the end is that we really deliver the science,” she said.

The facility is one that the nuclear physics community has been campaigning for for many years, to work towards a more complete understanding of nucleons and atomic nuclei in quantum chromodynamics, the physical theory that describes strong interactions, Gao noted. . It will also allow scientists to discover new physics beyond the Standard Model of particle physics, Gao said.

“This facility also gives us a wonderful opportunity to train a highly motivated scientific and technical workforce in this country,” she added.

In addition to his expertise in nuclear physics, Gao has a keen interest in promoting diversity, equity and inclusion in science.

Gao obtained his doctorate. in physics from the California Institute of Technology in 1994. Since then, she has held several positions in the field, including as assistant physicist at Argonne National Laboratory and assistant and associate professor of physics at Massachusetts Institute of Technology.

While at Duke, Gao also served as the Founding Professor of Physics and Vice Chancellor for Academic Affairs at Duke Kunshan University in Kunshan, China, where she spent some of her childhood years.

Gao’s research interests at Duke have included the structure of the nucleon, the search for exotic states of quantum chromodynamics, fundamental studies of low-energy symmetry to search for new physics beyond the standard model of electroweak interactions, and the development of polarized targets.

She was elected a Fellow of the American Physical Society in 2007 and won the U.S. Department of Energy’s Best Junior Researcher Award in 2000.

Brookhaven National Laboratory is supported by the US Department of Energy’s Office of Science. The Office of Science is the largest supporter of basic physical science research in the United States and works to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.

Follow @BrookhavenLab on Twitter or find us on Facebook.

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The muon and its oscillation https://polkinghorne.org/the-muon-and-its-oscillation/ Mon, 12 Apr 2021 07:00:00 +0000 https://polkinghorne.org/the-muon-and-its-oscillation/ There’s a lot of suspension on the unintended wobble. Muons, heavier cousins ​​of electrons, don’t behave as expected when thrown through a strong magnetic field, an Illinois lab reports. By teetering faster than expected, scientists say, they raise tantalizing questions about the accepted understanding of the fundamental laws of particle physics, the “standard model” that […]]]>

There’s a lot of suspension on the unintended wobble. Muons, heavier cousins ​​of electrons, don’t behave as expected when thrown through a strong magnetic field, an Illinois lab reports. By teetering faster than expected, scientists say, they raise tantalizing questions about the accepted understanding of the fundamental laws of particle physics, the “standard model” that describes particles (currently 17) and the forces that govern the subatomic world. .

Mainstream thinking suggests that all the forces we experience can be reduced to just four categories: gravity, electromagnetism, and, shaping the behavior of subatomic particles, the strong force and the weak force. The muon wobble suggests a fifth force that could provide an explanation for mysteries such as the accelerating expanding universe and the nature of dark matter, the invisible matter that astronomers say makes up a quarter of the mass of the universe.

Strange behaviour

Results announced last week from the Muon g-2 experiment at the Fermi National Accelerator Laboratory, or Fermilab, in Batavia – a team of 200 physicists from seven countries – appear to have successfully replicated a 20-year-old experiment on the strange behavior of muons and their deviation from the standard model remained unexplained. Separately, reports from the CERN Large Hadron Collider on the Franco-Swiss border of the decay of unstable B mesons into muons and electrons this week have also raised doubts about the model.

During a seminar and press conference last week, Fermilab physicist Dr. Chris Polly pointed to a graph displaying white space where their findings deviated from the theoretical prediction. “We can say with fairly high confidence that there must be something contributing to this white space. What monsters could be hiding there?

The work and its promising implications are far from conclusive, but scientists have likened it to the much-heralded 2012 discovery of the Higgs boson, a particle that impregnates other particles with mass. The ephemeral quantum world of the muon may be revealing its secrets.

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New muon measurements could rewrite particle physics | Smart News https://polkinghorne.org/new-muon-measurements-could-rewrite-particle-physics-smart-news/ Fri, 09 Apr 2021 07:00:00 +0000 https://polkinghorne.org/new-muon-measurements-could-rewrite-particle-physics-smart-news/ The 50-foot-wide hippodrome used to study muons traveled by barge around Florida and Mississippi, then by truck through Illinois. Reidar Hahn, Fermilab About 50 years ago, physicists came up with a rulebook to describe how fundamental particles interact to create the world as we know it. Since then, researchers have pushed this theoretical framework, called […]]]>

The 50-foot-wide hippodrome used to study muons traveled by barge around Florida and Mississippi, then by truck through Illinois.
Reidar Hahn, Fermilab

About 50 years ago, physicists came up with a rulebook to describe how fundamental particles interact to create the world as we know it. Since then, researchers have pushed this theoretical framework, called the Standard Model, to its limits in order to study its imperfections.

Today, the results of two particle physics experiments come close to uncovering a gap in the Standard Model.

The experiments focused on muons, which are similar to electrons. Both have electric charge and spin, causing them to oscillate in a magnetic field. But muons are more than 200 times larger than electrons, and they split into electrons and another particle, neutrinos, in 2.2 millionths of a second. Luckily, that’s just enough time to collect accurate measurements, with the right equipment, like a 50-foot-wide magnetic circuit.

Physicist Chris Polly of the Fermi National Accelerator Laboratory presented a graph at a seminar and press conference last week that showed a discrepancy between the theoretical calculation and actual measurements of muons moving through the racetrack.

“We can say with pretty high confidence that there has to be something contributing to that white space,” Polly said at the press conference, according to Dennis Overbye at the New York Times. “What monsters could be hiding there?”

The Standard Model aims to describe everything in the universe in terms of its fundamental particles, like electrons and muons, and its fundamental forces. The model predicted the existence of the Higgs boson particle, which was discovered in 2012. But physicists know that the model is incomplete: it takes into account three fundamental forces, but not gravity, for example.

A disconnect between theory and experimental results could help researchers uncover hidden physics and extend the Standard Model to more fully explain the universe.

“New particles, new physics could be just beyond our search,” Wayne State University particle physicist Alexey Petrov tells The Associated Press’ Seth Borenstein. “It’s tantalizing.”

The Standard Model requires such complex calculations that it took a team of 132 theoretical physicists, led by Aida El-Khadra, to come up with its prediction for the muon oscillation in the Fermi Lab experiment. The calculations predicted an oscillation lower than that measured by the Fermilab experiment.

This week’s results closely follow new findings from the Large Hadron Collider. Last month, LHC researchers showed a startling rate of particles left over after breaking up high-speed muons.

“The LHC, if you will, is almost like crashing two Swiss watches against each other at high speed. The debris comes out and you try to piece together what’s inside,” University of Manchester physicist Mark Lancaster, who worked on the Fermilab experiments, tells Michael Greshko at National geographic. At Fermilab, “we have a Swiss watch, and we look at it very, very, very, very carefully and precisely, to see if it does what we expect it to do. »

The Fermilab group used the same 50-foot-wide ring that was first used in the 2001 muon experiments. The researchers shoot a particle beam into the ring, where the particles are exposed to magnets superconductors. The beam particles decay into several other particles, including muons. Then those muons swirl around the racetrack several times before decaying, giving physicists a chance to measure how they interact with the magnetic field, writes Daniel Garisto for American Scientist.

To avoid bias, the instruments the researchers used to measure muons gave encrypted results. The key – a number written on a piece of paper and hidden in two offices at Fermilab and the University of Washington – remained secret until a virtual meeting in late February. When the key was entered into the spreadsheet, the results became clear: the experiment did not match the theory.

“We were all really ecstatic, excited, but also shocked, because deep down I think we’re all a bit pessimistic,” Fermilab physicist Jessica Esquivel tells National geographic.

If the results hold as more data from the experiment emerges, they would upend “every other calculation made” in the field of particle physics, says David Kaplan, a theoretical physicist at Johns Hopkins University. , to the Associated Press.

Freya Blekman, a physicist from the Free University of Brussels, who did not take part in the work, says National geographic that the work “is Nobel-worthy, no doubt,” if it holds up.

Results to date should be published in journals Physical examination letters, A&B physical examination, Physical examination A and physical examination d. These results come from only six percent of the data that the Fermilab experiment expects to collect. Between this six percent and the experimental results from 2001, there is a one in 40,000 chance that the difference between theory and experiment is in error.

“It’s strong evidence that the muon is sensitive to something that’s not in our best theory,” says University of Kentucky physicist Renee Fatemi. New York Times.

But particle physics demands that researchers bring that down to a one in 3.5 million chance. The research team could have the final results by the end of 2023.

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Tiny, flickering muon just shook particle physics to its core https://polkinghorne.org/tiny-flickering-muon-just-shook-particle-physics-to-its-core/ Wed, 07 Apr 2021 07:00:00 +0000 https://polkinghorne.org/tiny-flickering-muon-just-shook-particle-physics-to-its-core/ The results of one of the most eagerly awaited experiments in particle physics have arrived, and they could be about to make every researcher’s wildest dreams come true: they might, might, shatter physics. as we know it. Evidence from the Fermi National Accelerator Laboratory near Chicago suggests a tiny subatomic particle known as the muon […]]]>

The results of one of the most eagerly awaited experiments in particle physics have arrived, and they could be about to make every researcher’s wildest dreams come true: they might, might, shatter physics. as we know it.

Evidence from the Fermi National Accelerator Laboratory near Chicago suggests a tiny subatomic particle known as the muon wobbling far more than theory predicts. The best explanation, physicists say, is that the muon is being pushed by types of matter and energy completely unknown to physics.

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Coffea accelerates the analysis of particle physics data https://polkinghorne.org/coffea-accelerates-the-analysis-of-particle-physics-data/ Fri, 19 Feb 2021 08:00:00 +0000 https://polkinghorne.org/coffea-accelerates-the-analysis-of-particle-physics-data/ Analyzing the mountains of data generated by the Large Hadron Collider at the European CERN laboratory takes so long that even computers need coffee. Or rather, Coffea — Columnar Object Framework for Effective Analysis. A package in the Python programming language, Coffea (pronounced like the stimulating drink) speeds up the analysis of massive datasets in […]]]>

Analyzing the mountains of data generated by the Large Hadron Collider at the European CERN laboratory takes so long that even computers need coffee. Or rather, Coffea — Columnar Object Framework for Effective Analysis.

A package in the Python programming language, Coffea (pronounced like the stimulating drink) speeds up the analysis of massive datasets in high-energy physics research. Although Coffea streamlines the calculations, the main objective of the software is to optimize the scientists’ time.

“A human’s efficiency in producing scientific results is of course affected by the tools you have,” said Matteo Cremonesi, postdoctoral fellow at the US Department of Energy’s Fermi National Accelerator Laboratory. “If it takes me more than a day to get a single number out of a calculation – which often happens in high-energy physics – it’s going to hurt my effectiveness as a scientist.”

Frustrated by the tedious manual labor they faced when writing computer code to analyze LHC data, Cremonesi and Fermilab scientist Lindsey Gray assembled a team of Fermilab researchers in 2018 to adapt the techniques of big data to solve the most difficult questions of high energy physics. . Since then, a dozen research groups on the CMS experiment, one of the two large general-purpose detectors of the LHC, have adopted Coffea for their work.

A dozen research groups on the CMS experiment at the Large Hadron Collider have adopted the Coffea data analysis tool for their work. Using information about particles generated in collisions, Coffea enables broad statistical analyzes that improve researchers’ understanding of the underlying physics, enabling faster run times and more efficient use of computing resources. Photo: CERN

Using information about particles generated in collisions, Coffea enables broad statistical analyzes that refine researchers’ understanding of the underlying physics. (The LHC data processing facilities perform the initial conversion of the raw data into a format that particle physicists can use for analysis.) A typical analysis of the current LHC dataset involves the processing of approximately 10 billion particle events that can total over 50 terabytes of data. That’s the data equivalent of about 25,000 hours of streaming video on Netflix.

At the heart of Fermilab’s analysis tool is the move from a method known as event loop analysis to one called column analysis.

“You have a choice if you want to iterate over each row and do an operation in the columns or if you want to iterate over the operations you do and attack all the rows at once,” explained Fermilab postdoctoral researcher Nick Smith, the main developer of Coffea. “It’s kind of an order of operations.”

For example, imagine that for each row, you wanted to sum the numbers in three columns. In the event loop analysis, you will start by adding the three numbers in the first line. Then you will add the three numbers in the second row, then move on to the third row, and so on. With a columnar approach, on the other hand, you’ll start by adding the first and second columns for all rows. Then you would add this result to the third column for all rows.

“Either way, the end result would be the same,” Smith said. “But there are trade-offs you make under the hood, in the machine, that have a big impact on efficiency.”

In datasets with many rows, columnar analysis performs about 100 times faster than event loop analysis in Python. Yet before Coffea, particle physicists primarily used event loop analysis in their work, even for datasets with millions or billions of collisions.

The Fermilab researchers decided to pursue a columnar approach, but they faced a daunting challenge: high-energy physics data cannot easily be represented in tabular form with rows and columns. One particle collision might produce a multitude of muons and few electrons, while the next might produce no muons and many electrons. Using a library of Python code called Awkward Array, the team devised a way to convert the jagged, nested structure of LHC data into arrays compatible with columnar analysis. Generally, each row corresponds to a collision, and each column corresponds to a property of a particle created during the collision.

The benefits of Coffea extend beyond faster execution times (minutes instead of hours or days when it comes to interpreted Python code) and more efficient use of computing resources. The software takes mundane coding decisions out of the hands of scientists, allowing them to work at a more abstract level with less chance of making mistakes.

“Researchers aren’t here to be programmers,” Smith said. “They are there to be data scientists.”

Cremonesi, who researches dark matter at CMS, was among the first researchers to use Coffea without a backup system. At first, he and the rest of the Fermilab team actively sought to persuade other groups to try the tool. Now researchers frequently approach them asking how to apply Coffea to their own work.

Soon, the use of Coffea will extend beyond the CMS. Researchers at the Institute for Software Research and Innovation for High Energy Physics, supported by the US National Science Foundation, plan to integrate Coffea into future CMS analysis systems and ATLAS, the LHC’s other large general-purpose experimental detector. An LHC upgrade known as the High-Luminosity LHC, due for completion in the mid-2020s, will record around 100 times more data, making the efficient data analysis offered by Coffea even more valuable for international collaborators in the LHC experiments.

Going forward, the Fermilab team also plans to break Coffea down into multiple Python packages, allowing researchers to use only the stuff that’s relevant to them. For example, some scientists use Coffea primarily for its histogram function, Gray said.

For the Fermilab researchers, the success of Coffea reflects a necessary shift in the mindset of particle physicists.

“Historically, the way we do science has focused a lot on the material component of creating an experiment,” Cremonesi said. “But we have reached an era in physics research where managing the software component of our scientific process is just as important.”

Coffea promises to synchronize high-energy physics with recent advances in big data in other scientific fields. This cross-pollination may prove to be Coffea’s most important benefit.

“I think it’s important for us as a high-energy physics community to think about what kind of skills we’re imparting to the people we’re training,” Gray said. “Ensuring that we, as a field, are relevant to the rest of the world when it comes to data science is a good thing to do.”

US participation in CMS is supported by the Department of Energy Office of Science.

Fermilab is supported by the US Department of Energy’s Office of Science. The Office of Science is the largest supporter of basic physical science research in the United States and works to address some of the most pressing challenges of our time. For more information, visit science.energy.gov.

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Secondary school teachers, meet particle physics https://polkinghorne.org/secondary-school-teachers-meet-particle-physics/ Tue, 05 Jan 2021 08:00:00 +0000 https://polkinghorne.org/secondary-school-teachers-meet-particle-physics/ Imagine this: a stationary object such as a vase suddenly explodes, sending fragments flying. Given the final energies and momentum of the fragments, can you determine the mass of the object before it shattered? Dave Fish introduces his students to this common momentum conservation problem, with a twist. Instead of describing the explosion of a […]]]>

Imagine this: a stationary object such as a vase suddenly explodes, sending fragments flying. Given the final energies and momentum of the fragments, can you determine the mass of the object before it shattered?

Dave Fish introduces his students to this common momentum conservation problem, with a twist. Instead of describing the explosion of a macroscopic object like a vase, it describes the transformation of a top quark and a top antiquark into other fundamental particles.

Fish teaches high school physics and is a professor in residence at the Perimeter Institute for Theoretical Physics in Ontario. In Canada, particle physics is “one of those things that teachers tend to leave until the end of class and then they run out of time,” says Fish. “Most of us as secondary school teachers feel overwhelmed by the content.”

Particle physics makes its appearance in the curriculum of the International Baccalaureate, a program recognized as an entrance qualification to higher education by many universities around the world. The subject also appears in some state curricula, such as that of North Rhine-Westphalia in Germany. But in general, “there aren’t many programs that deal explicitly with particle physics,” says Jeff Wiener, head of teacher programs at CERN. “Those who do usually focus on rather boring stuff like, ‘Name two leptons.'”

Put particles in the program

Many high school science teachers who would like to teach particle physics say they feel insufficiently informed about the subject or don’t know how to include it without sacrificing required curriculum topics.

Fish and Wiener are two of many people hoping to change that. They see many opportunities to incorporate particle physics into standard curricula focused on general physics concepts. To teach conservation of momentum, try using real data from the discovery of the top quark (an activity developed by educators at the US Department of Energy’s Fermi National Accelerator Laboratory). To demonstrate the movement of charged particles in magnetic fields, show photographs of particle detectors called bubble chambers. To give an example of circular motion, discuss the mystery of dark matter.

One of Fish’s former students, Nikolina Ilic, considers a dark matter project she undertook in her class a turning point in her education. “I realized that we don’t know what 95% of the universe is made of, and that blew my mind,” she says. “That’s when I decided to pursue particle physics.”

Ilic continued her doctoral research at CERN, where she contributed to the statistical analysis for the discovery of the Higgs boson.

In the years he is not teaching high school students, Fish leads workshops at the Perimeter Institute to help other teachers bring particle physics into their classrooms. Each year, approximately 40 or 50 teachers from Canada and other countries attend a week-long EinsteinPlus workshop, participating in a variety of collaborative activities designed to teach them about modern physics. One of the most popular is a card sorting game that teaches standard pattern patterns and symmetries. In each activity, “we ask the teachers to be the students and ask the questions that the students would ask,” says Fish.

Fermilab organizes similar teacher workshops covering various physics topics for primary to secondary school teachers.

As the COVID-19 pandemic has forced many programs to move online, Fermilab has focused on finding ways to interact with teachers and students virtually. “We have career talks with lab staff, classroom presentations that we create with teachers and host virtually, Virtual Ask-a-Scientist, and Saturday Morning Physics,” says Amanda Early, program manager at Education at Fermilab which runs K-12 physical science programs. .

Each year, Fermilab organizes programs for educators and students, engaging them with the science of Fermilab. “The more you expose students to particle physics — the size and scale of it and its benefits — the more opportunities children will see to engage in science,” says Early.

In 2020, one of the Education Group’s summer science institutes focused specifically on helping high school teachers adapt modern physics lessons to the next-generation science standards used in many US states. Approximately 80 teachers from the Chicago area and across the country participated in the five-day interactive workshop, which in 2020 was offered online.

Next Generation Science Standards do not explicitly mention particle physics. But the cross-cutting concepts and scientific and engineering practices that frame them dovetail nicely with the subject, says David Torpe, an Illinois high school science teacher who has led professional development workshops at Fermilab for six years.

“Let’s talk about process, let’s talk about how particle physicists analyze data, let’s talk about how they solve problems,” says Torpe. “The ideas of energy and cause and effect naturally fit in too. I think a good strategy is to find a bit of particle physics that you find interesting and insert it here or there.

Bringing teachers to CERN, and CERN to teachers

Across the Atlantic, in Europe, CERN’s teacher programs attract more than 1,000 secondary school teachers from around the world to Geneva each year. Between physics lessons, professors visit the laboratories and have question-and-answer sessions with CERN scientists.

“The idea was that when we returned to Mexico, we would be ambassadors and encourage certain students to see that it is possible to go and do research at CERN”, explains Eduardo Morales Gamboa, who followed the program of teaching Spanish in 2019.

Since visiting the massive CMS detector and seeing particle tracks in a homemade cloud chamber, he has incorporated particle physics – and the many useful applications that have come from it – into his class discussions of intersections. of science, technology and society. Eventually, he says, he hopes to build a cloud chamber with his students.

According to Wiener, Morales Gamboa’s experience is common. Many alumni of teacher programs even return to CERN, this time with their students for the trip, to ignite the next generation’s enthusiasm for particle physics.

The success of CERN’s outreach efforts stems in part from integration with physics education research. Indeed, CERN teacher programs are designed to equip participants with knowledge not only of particle physics, but also of the best pedagogical practices for science education.

One such practice is to have students move through “predict-observe-explain” cycles. “You encourage students to make a prediction of what will happen before doing the experiment. This way you make sure that they first activate their previous knowledge and become curious about the result,” says Julia Woithe, who coordinates the hands-on learning labs at CERN. “Then, if they’re surprised by the observed result, they have to work out as a team how to explain the differences between their predictions and their observations. This usually leads to a powerful ‘eureka!’ moment.”

In addition to organizing events at CERN, Wiener traveled to India to collaborate with educators from the International School of Geneva in the first science education program in South Asia last year. Eighty teachers from the region participated in the week-long program at Shiv Nadar Noida School in New Delhi.

Vinita Sharat, the school’s STEAM coordinator, taught particle physics for a decade but remembers initially facing resistance from organizations where she previously worked. “The first challenge is to change the mentality of authority,” she says. “They asked why I was teaching it since it’s not part of the curriculum.”

His students, on the other hand, had no scruples. Some found particle physics so fascinating that they stayed online until midnight to discuss quarks and leptons with Sharat. “Students will always be ready to learn something related to nature,” she says.

Sharat fosters the creative side of students in her particle physics classes by encouraging them to write poems, make videos or choreograph dances to explain the concepts they are studying. Like Fish, Sharat stayed in touch with several former students whom she inspired to pursue careers in physics.

“The basis of everything”

After the CERN program at her school, Sharat hopes more teachers across South Asia will incorporate particle physics into their classrooms. And Wiener plans to lead more teaching workshops around the world in the future.

For now, COVID-19 has interrupted in-person professional development workshops. But teachers can still access some online resources: CERN’s hands-on learning lab S’Cool LAB (until recently run by Woithe), the Perimeter Institute, Fermilab and QuarkNet offer free downloads of their teaching materials interactive.

For Morales Gamboa, the benefits of teaching particle physics in high school go beyond encouraging a few students to pursue careers in this field. Talking about connections to engineering shows how abstract scientific ideas are linked to everyday life, while describing massive international projects conveys the key collaborative spirit of modern science.

Stacy Gates, an Illinois high school science teacher who taught at Fermilab’s Summer High School Physics Institute alongside Torpe in 2020, points out that teaching particle physics fosters critical thinking. “I encourage my students to question me when they don’t believe that particles can behave in a certain way,” she says. “It’s such an important skill because that’s what scientists do. They question everything and try to prove and disprove.

Sharat agrees that particle physics holds valuable lessons. No matter where her students go in life, she wants them to understand that “particle physics is the foundation of everything,” she says.

“We should know the reason for our existence. We should know what we are made of.

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Scientists work to shed light on the Standard Model of particle physics https://polkinghorne.org/scientists-work-to-shed-light-on-the-standard-model-of-particle-physics/ Thu, 05 Nov 2020 08:00:00 +0000 https://polkinghorne.org/scientists-work-to-shed-light-on-the-standard-model-of-particle-physics/ Typical magnetic field variations as mapped by the trolley at different positions in the storage ring of the Muon g-2 experiment, presented at the parts per million level. Credit: Argonne National Laboratory. As scientists await the highly anticipated first results of the Muon g-2 experiment at the US Department of Energy’s (DOE) Fermi National Accelerator […]]]>

Typical magnetic field variations as mapped by the trolley at different positions in the storage ring of the Muon g-2 experiment, presented at the parts per million level. Credit: Argonne National Laboratory.

As scientists await the highly anticipated first results of the Muon g-2 experiment at the US Department of Energy’s (DOE) Fermi National Accelerator Laboratory, collaborating scientists at the DOE’s Argonne National Laboratory continue to employ and to maintain the unique system that maps the magnetic field in the experiment with unprecedented precision.

Argonne scientists have improved the measurement system, which uses an advanced communications system and new magnetic field probes and electronics to map the field in the 45-meter circumference ring in which the experience.

The experiment, which started in 2017 and continues today, could have big implications for the field of particle physics. As a follow-up to a past experiment at the DOE’s Brookhaven National Laboratory, it has the power to affirm or refute previous findings, which could shed light on the validity of parts of the reigning standard model of science. particle physics.

High precision measurements of large quantities in the experiment are crucial to produce meaningful results. The main quantity of interest is the muon’s g-factor, a property that characterizes the magnetic and quantum mechanical attributes of the particle.

The standard model predicts very accurately the value of the g-factor of the muon. “Because the theory predicts this number so clearly, testing the g-factor by experiment is an effective way to test the theory,” said Simon Corrodi, a postdoctoral fellow appointed in the High Energy Physics (HEP) division of Argonne. . “There was a large discrepancy between the Brookhaven measurement and the theoretical prediction, and if we confirm this discrepancy, it will signal the existence of undiscovered particles.”

Just as the Earth’s axis of rotation precedes – meaning the poles move gradually in circles – the spin of the muon, a quantum version of angular momentum, precedes in the presence of a magnetic field. The strength of the magnetic field surrounding a muon influences the rate at which its spin precedes. Scientists can determine the g-factor of the muon by measuring the rate of spin precession and the strength of the magnetic field.

The more precise these initial measurements are, the more conclusive the final result will be. Scientists are on their way to make accurate field measurements at 70 parts per billion. This level of precision allows the final calculation of the g-factor to be accurate to four times the precision of the results of the Brookhaven experiment. If the experimentally measured value differs significantly from the value expected from the Standard Model, this may indicate the existence of unknown particles whose presence disturbs the local magnetic field around the muon.

Trolley ride

During data collection, a magnetic field causes a beam of muons to travel around a large hollow ring. To map the magnetic field strength throughout the ring with high resolution and precision, scientists designed a cart system to drive measurement probes around the ring and collect data.

Heidelberg University developed the cart system for the Brookhaven experiment, and Argonne scientists refurbished the equipment and replaced the electronics. In addition to the 378 probes mounted in the ring to continuously monitor field drifts, the cart contains 17 probes that periodically measure the field with higher resolution.

“Every three days, the cart circles the ring in both directions, taking about 9,000 measurements per probe per direction,” Corrodi said. “Then we take the measurements to build slices of the magnetic field and then a full 3D map of the ring.”

Scientists know the cart’s exact location within the ring thanks to a new barcode reader that registers marks at the bottom of the ring as it moves.

The ring is filled with a void to facilitate controlled muon decay. To preserve the vacuum inside the ring, a garage connected to the ring and the vacuum stores the trolley between measures. Automating the process of loading and unloading the cart into the ring reduces the risk of scientists compromising the vacuum and magnetic field by interacting with the system. They also minimized the power consumption of the cart’s electronics to limit the heat introduced into the system, which would otherwise disrupt measurement accuracy in the field.

Scientists work to shed light on the Standard Model of particle physics

Fully assembled cart system with wheels for rolling on rails and the new external barcode reader for exact position measurement. The 50 cm long cylindrical shell houses the 17 NMR probes and the custom-made reading and control electronics. Credit: Argonne National Laboratory.

The scientists designed the trolley and the garage to operate in the strong magnetic field of the ring without influencing it. “We used a motor that operates in a strong magnetic field and with a minimal magnetic signature, and the motor moves the cart mechanically, using ropes,” Corrodi said. “This reduces noise in the field measurements introduced by the equipment.”

The system uses as little magnetic material as possible, and scientists tested the magnetic footprint of each component using test magnets at the University of Washington and Argonne to characterize the system’s overall magnetic signature. cart.

The power to communicate

Of the two cables pulling the trolley around the ring, one of them also serves as a power supply and communication cable between the control station and the measurement probes.

To measure the field, scientists send a radio frequency through the cable to the cart’s 17 probes. The radio frequency rotates the spins of the molecules inside the probe in the magnetic field. The radio frequency is then cut off at the right moment, causing the spins of the water molecules to precess. This approach is called nuclear magnetic resonance (NMR).

The frequency at which the probes’ rotations precede depends on the magnetic field in the ring, and a digitizer on board the cart converts the analog radio frequency into multiple digital values ​​communicated via cable to a monitoring station. At the control station, scientists analyze the digital data to construct the spin precession frequency and, from this, a complete map of the magnetic field.

During the Brookhaven experiment, all signals were sent simultaneously over the cable. However, due to the conversion from analog to digital signal in the new experiment, a lot more data has to travel over the wire, and this increased speed could disrupt the very precise radio frequency needed for the probe measurement. To avoid this disruption, the scientists separated the signals in time, switching between the radio frequency signal and the data communication in the cable.

“We feed the probes a radio frequency via an analog signal,” Corrodi said, “and we use a digital signal to communicate the data. The cable switches between these two modes every 35 milliseconds.”

The tactic of switching between signals traveling through the same cable is called “time division multiplexing”, and it helps scientists achieve specifications not only for accuracy, but also for noise levels. An upgrade of the Brookhaven experiment, time division multiplexing allows for higher resolution mapping and new capabilities for analyzing magnetic field data.

Upcoming results

The field-mapping NMR system and its motion control were successfully commissioned at Fermilab and operated reliably for the first three data-taking periods of the experiment.

Scientists achieved unprecedented precision for field measurements, as well as record uniformity of the ring’s magnetic field, in this Muon g-2 experiment. Scientists are currently analyzing the first set of data from 2018 and plan to publish the results by the end of 2020.

The scientists detailed the complex setup in a paper titled “Design and Performance of a Vacuum Magnetic Field Mapping System for the Muon g-2 Experiment,” published in the Instrumentation review.


Muons tell tales of undiscovered particles


More information:
S. Corrodi et al, Design and performance of a vacuum magnetic field mapping system for the Muon g-2 experiment, Instrumentation review (2020). DOI: 10.1088/1748-0221/15/11/P11008

Provided by Argonne National Laboratory

Quote: Scientists work to shed light on the Standard Model of Particle Physics (2020, November 5) Retrieved February 10, 2022 from https://phys.org/news/2020-11-scientists-standard-particle-physics .html

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